Tubular connectors for fluid conveying conduits are generally comprised of a tube and an attached shell and are usually manufactured from a metallic material. A conduit is coupled with the tubular connector in order to form an assembly. The conduit, usually of an elastic material, is inserted into the tubular connector such that an end of the tube is inserted into the conduit and the shell surrounds the conduit. The shell is inwardly or radially deformed so that the conduit is compressed between the tube and shell, thus retaining and sealing the combination.
Most currently available tubular connectors retain the shell component by machining a notch into the outer surface of the tube, then fitting an end of the shell into the notch. A typical example of this type of design is shown in a prior art construction, such as U.S. Pat. No. 5,984,376 to Lampe. A disadvantage with this type of design is that the machined notch can damage the tube thus creating an area prone to fatigue failure.
Another method of forming an attachment of the conduit to the tubular connector is shown in U.S. Pat. No. 5,722,150 to Swanson, III. This method uses a pair of bead lock rings with an expandable ring compressed therebetween. The shell is then advanced over the ring and inwardly crimped. The novel process of the present invention differs from this method by compressing the shell between two formed beads and avoids adding a further component, the expandable ring.
Another method of attaching the shell to the tube is shown in U.S. Pat. No. 5,961,157 to Baron et al. An embodiment of this method shows the shell compressed between two beads formed in the tube. The tube is separate from the nipple, unlike the present design, and also adds a further component to the connector.
Still another tubular connector using a bead to attach the shell to the tube is shown in U.S. Pat. No. 5,387,016 to Joseph et al. In this design, the shell is compressed between a formed bead and a shoulder of the tube. The method of forming the bead differs from that of the present invention in that stress is applied to the end of the nipple to form the bead.
Up to this time, typical uses of 5000 series aluminum alloys have been restricted to primarily shell metal applications. Due to its excellent corrosion resistance and overall strength, it is a desirable substitute same for the commonly used 3000 series aluminum alloys. But due to its hardness, the 5000 series is difficult to machine and is difficult to roll-form without damaging same. Therefore, most roll-formed methods employ the 3000 series alloys since they are soft and easy to form even though they lack the noted attributes of the 5000 series alloys.